So Warren, with his enthusiasm, tried to persuade Frank and me to shift our interest from the microorganisms we were then interested in to cell culture. We both resisted; we resisted for several weeks. Frank dug his heels in so hard he wouldn't even consider it. On the other hand, I was less intractable and agreed to at least learn the technique. And I compromised with Warren, I said, 'Okay, I'll allow you to teach me cell culture', with the understanding that I will try to grow these organisms in cell culture. We knew nothing about their behaviour under those circumstances, and it seemed like an attractive thing to do, because it was known that these organisms that were then highly associated with veterinary diseases, diseases in chickens, turkeys, pigs, etc., had a cellular affinity. And so that bridge was okay with me and, of course, it was okay with Warren, because it gave him an opportunity to teach us this... teach me this technique, which he did do.

Leonard Hayflick (b. 1928), the recipient of several research prizes and awards, including the 1991 Sandoz Prize for Gerontological Research, is known for his research in cell biology, virus vaccine development, and mycoplasmology. He also has studied the ageing process for more than thirty years. Hayflick is known for discovering that human cells divide for a limited number of times in vitro (refuting the contention by Alexis Carrel that normal body cells are immortal), which is known as the Hayflick limit, as well as developing the first normal human diploid cell strains for studies on human ageing and for research use throughout the world. He also made the first oral polio vaccine produced in a continuously propogated cell strain - work which contributed to significant virus vaccine development.